We used to live in a one-level co-op in Washington, D.C. During that time Kate had a bum knee that hurt off and on, and gradually became chronic. A couple of months after moving to Frederick, Md., though, her knee stopped hurting.

Finally we realized that the one big difference was stairs. In our co-op, she rarely used the stairs. In our three-level town house, Kate walks the stairs frequently.

Such a simple change in lifestyle - such a dramatic change. Whether she will develop arthritis later on, we don't know.

Many older people, though, feel joint pain and stiffness sooner or later in their lives and develop osteoporosis or arthritis.

"By age 40, about 90 percent of us have signs of osteoarthritis that can be seen on X-rays of the weight-bearing joints (the hips and knees, for example), but symptoms of pain and stiffness usually don't start until later in life," says a Johns Hopkins White Paper on Arthritis. Both osteoarthritis and arthritis affect older people.

Over 20 million people in the U.S. have osteoarthritis (the most common form of arthritis), the white paper says, and is the most frequent cause of physical disability in older people.

Many control their pain initially by taking over-the-counter drugs, such as Aleve or aspirin. If these fail, then doctors can prescribe stronger medicine and in the worst case put shots into the painful area.

But people themselves can affect how the diseases progresses and lessen their pain.

How?

Through dieting, exercise and injury prevention.

DIET

Losing weight is especially important for obese people. Losing just 11 pounds can decrease the risk of knee osteoarthritis by 50 percent since it takes pressure off joints, Johns Hopkins reports.

People who are only a little overweight receive the same benefit by controlling what they eat and shedding those extra pounds.

EXERCISE

Mild to moderate exercise strengthens the muscles that support weight-bearing joints. Preferably it should be done most weekdays. This includes such exercises as walking, swimming and aerobics.

Exercise gurus, as well as Johns Hopkins, confirm that it's OK to break your exercise routine into 10-minute periods throughout the day. Personally, I prefer to follow my routine over a continuous period.

INJURY PREVENTION

Studies show that people whose jobs required them to spend an hour a day on their knees or squatting were almost twice as likely to have osteoarthritis in their knees.

Common sense says that a partial solution lies in finding ways to change job requirements or to minimize the effects, such as by taking frequent breaks, standing up, walking for a few minutes regularly throughout the work day.

Computer users should stretch and stand up every 15 minutes or so.

Get a note from your doctor, if your boss objects.

Along with following traditional medical advice, many people also use complementary means to make their pain more bearable.

Those ways include music.

A small study of 60 people who listened to music for an hour a day found that this "can reduce pain, depression and other symptoms associated with chronic pain," Johns Hopkins reports. They suffered long-term pain from osteoarthritis, rheumatoid arthritis or back problems.

In the study, the 60 people were divided into three groups: one group chose its own music; the second group had music chosen by the researchers for its soothing characteristics; and the control group didn't listen to any music.

The two groups that listened to music "showed significant improvements" in depression and disability and felt they had power over their pain, ranging from 12 percent to 21 percent. The control group, though, experienced a small increase in pain. That study, though limited to a few people, proves the truth of the old adage (paraphrased), "Music hath charms to soothe humans and beasts."

I'm going to start listening to my favorite jazz artists right away.

RESOURCES

The Arthritis Foundation offers a six-week self-management program through its chapters to teach people how to reduce and manage their joint pain. Box 7669, Atlanta, GA 30357-0669; 800-568-4045 or 404-872-7100; www.arthritis.org.